Grinding device for cloth cutting machines and the like



Nov. 10, 1959 2,911,772

GRINDING DEVICE FOR CLOTH CUTTING MACHINES AND THE LIKE Filed March 25,1958 H. GRONEMEIER 2 Sheets-Sheet 1 IN VE N TOR A O/IIL QoIrEME/Er Nov.10, 1959 H. GRONEMEIER 2,911,772

GRINDING DEVICE FOR CLOTH CUTTING MACHINES AND THE LIKE F'iied March 25,1958 2 Sheets-Sheet 2 //V MENTOR l llll-llllll 9/712 42 em a for @aUnite a GRINDING DEVICE FOR CLOTH CUTTING MACHINES AND THE LIKE HeinzGronemeier, Bonn-Buschdorf, Germany, assignor to E. Hoogland,Zuschneidernaschinenfabrik, Bonn- Nord, Germany The present inventionrelates to a grinding device for cloth cutting machines. Heretoforeknown grinding devices employed for cloth cutting machines are providedwith grinding discs or grinding belts which during their grindingoperation are passed along the knives to be ground. This type ofgrinding device has various drawbacks.

Grinding devices operating with grinding discs have the drawback thatthe cutting angle changes continuously in view of the grinding down ofthe knives and the wearing off of the grinding discs. In extremesituations, such grinding devices become so dull that the ground cuttingedge will not cut any longer. When employing grinding discs, the groundsurface of the cutting knives becomes hollow. If the ground surface ofthe cutting knives is ground hollow, the cutting edge will more or lesseasily fold over depending on the material of the cutting edge. Inaddition thereto, the grinding discs become untrue in a relatively shorttime and crack so that a relatively frequent exchange of the grindingdiscs will become necessary.

Surfaces ground by grinding belts become crowned due to lack of uniformgrain structure or to the shimmying of the grinding belts. A groundcrowned cutting edge easily burns out by overheating due to excessivefriction.

Due to the wear of the grinding discs and grinding belts during thegrinding operation, abrasive powder is formed which enters parts of thedevice and the guiding means for the knives thereby bringing about apremature wear of these elements. Furthermore, with the heretofore knowngrinding devices, a burr is formed on the cutting edges of the knivesand also a grinding soft zone is formed whereby the maintenance of theproper cut of the knives is greatly afiected.

Finally, the dimensions and arrangement of the heretofore known grindingdevices greatly affect the visibility during the grinding operation.

It is, therefore, an object of the present invention to provide agrinding device of the type involved, which will overcome the abovementioned drawbacks.

It is another object of this invention to provide a grinding device forcloth cutting machines, which will pro duce a straight, plane, razorblade sharp V-shaped ground surface with always the same cutting angle.

It is a further object of this invention to provide a grinding devicefor cloth cutting machines, which will make it possible to grind thecutting knives so as to cause the same always to produce the same cut.

It is a still further object of this invention to provide a grindingdevice of the type set forth in the preceding paragraphs, which willconsiderably reduce the wear of the cutting knives to be ground thereby.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

Fig. l is a front view of a grinding device according States Patent tothe present invention in connection with a vertical cloth cuttingmachine.

Fig. 2 is a side view of the machine shown in Fig. 1.

Fig. 3 illustrates the grinding unit according to the invention inopened condition.

Fig. 4 shows the grinding unit of Fig. 3 in closed condition.

Fig. 5 illustrates on a somewhat larger scale than Figs. 1 to 4 thefront view of the grinding device according to the invention in itsgrinding position, but with the blocking mechanism for the currentsupply in open position.

Fig. 5a illustrates a front view of the grinding device during thegrinding operation.

Fig. 6 is a side view of the arrangement shown in Fig. 5.

Fig. 7 illustrates the grinding unit itself during the grindingoperation.

Fig. 8 illustrates the grinding unit of Fig. 7 with one arm tiltedoutwardly in order more clearly to show the cutting angle.

General arrangement The grinding device according to the presentinvention is characterized primarily in that the grinding elementscomprising diamond chips or diamond dust bound ceramically or byvegetable or mineral binding means are arranged in supports which areadapted to press the grinding elements against the cutting edge of thecutting knife in such a way that the diamond chips or the diamond dustacts upon said cutting edge.

The supports for the grinding elements may, in conformity with thepresent invention, be mounted on plierlike rod-shaped arms tiltable in ahorizontal plane about a pivot. These arms are adapted by pull or bypressure, for instance by a tension spring connected to said arms, to bepressed from both sides against the cutting edge of the knife.

The device according to the present invention will produce a straight,plane, razor blade sharp ground surface of V-shape which will alwayshave the same angle and a proper fine surface. The surface qualitycorresponds to that of a lapped cutting edge.

The maintenance of the cut of the knife as well as the precision of thecut is dependent on the quality of the surface of the knife.

The grinding device according to the present invention, therefore,brings about a considerable improvement in the surface quality of theground cutting edge of the knife and Will produce a cutting edge whichwill last considerably longer than cutting edges produced withheretofore known grinding devices for the purpose involved. The newgrinding device or, more specifically, the cut produced thereby, willprevent the danger that threads are pulled out of the fabric while it isbeing cut by the cutting knife. Experience has proved that the grindingdevice according to the invention reduces the wear of the knifeto onequarter and even one sixth of the wear of knives ground by heretoforeknown grinding devices.

The grinding elements of the grinding device according to the presentinvention are for all practical purposes not subjected to any wear atall so that an exchange of these grinding elements is hardly evernecessary. The harmful formation of abrasive dust will be avoided. Achange of the original grinding angle due to the wear of the grindingelement will likewise be avoided.

A further feature of the grinding device according to the inventionconsists in that the supports for the grinding elements are tiltableabout a vertical axis for adjusting any desired grinding angle so thatit will be possible to adjust the grinding angle in a manner which ismost favorable for the respective fabric to be cut.

Structural arrangement Referring now to the drawings in detail, Figs. 1and 2 illustrate a cloth cutting machine 2 mounted on a foot 1 andprovided with a vertical knife 3 to be ground .by a grinding device 4according to the invention. The grinding device 4 is mounted on thecover 5 of the cutting machine 2. The grinding device 4 is designed asindependent unit equipped with its own driving motor 6 and is adaptedeasily to be mounted on any cloth cutting machine.

The grinding device is driven by motor 6 which preferably represents areversible electric motor. This drive is effected through a transmission7 which in its turn drives a threaded spindle in the housing of thegrinding device 4. Mounted on the threaded spindle is a nut (not shownin the drawing) which carries a tubular guiding element 8 and bringsabout the upward and downward movement of said guiding element 8. Thelower end of the guiding element 8 carries the grinding unit proper. Aswillbe evident from Figs. 3 and 4, the said grinding unit comprisesplier-like tiltable supporting arms 9, 9a. The front ends of said arms9, 9a have angularly adjustably mounted thereon holding elements 11, 11afor the grinding elements 12, 12a so that the latter can be adjustedrelative to each other in conformity with a desired variable grindingangle 10. The grinding angle is adjusted by turning the holding elements'11, Ha for the grinding elements 12, 12a about the pivots 24, 24arespectively. After the angle 10 has thus been adjusted, the holdingelements 11, 11a are held in their respective position by any convenientmeans as for instance set screws or clamping screws. The arms 9, 9a areadapted to straddle a rod 14 which carries the pressing element 13 forthe cloth to be cut, and are also adapted to press the grinding elements12, 12a against the knife 3. When the grinding unit occupies its upperposition, the holding arms 9, 9a are tilted away from each other by theabutment cam members 15, 15a so that the said arms will not impair thevisibility during the cutting of the cloth. This represents aconsiderable advantage over the heretofore known grinding devices of thetype involved, in which due to mechanisms of considerable dimensions,for instance by drives mounted in the holding arms for driving thegrinding discs, the visibility is greatly impeded.

The drive for the knife of the cutting machine is controlled by a switch17 (see Fig. 2). A push button switch 16 (see Fig. 1) controls theoperation or standstill of the grinding device.

The supply of current to the grinding device is interrupted as long asthe cloth pressing element 13 does not occupy its lowermost end positionin order to prevent the grinding unit from moving against the pressingelement 13.

Figs. 5, 5a and 6 illustrate a blocking mechanism which comprises tworesilient contact arms 18, 18a with contacts 19, 19a. These contacts arepressed against each other and thereby closed in the end position onlyof the pressing element 13. This pressing of the contacts 19, 19aagainst each other is effected by a bolt 20 connected to the rod 14supporting the pressing element 13. It is only when said contacts 19,19a have been closed (Fig. 5a) that the guiding element 8 of thegrinding unit can start its downward movement. During this downwardmovement, the arms 9, 9a will due to the effect of the tension spring 21slide along the cams 15, 15a until the grinding elements 12, 12a due tothe force of the tension spring 21 are pressed at a grinding angledetermined by the adjustment of the holding elements 11, 11a against thecutting edge 22 of the quickly reciprocating knife 3 as shown in Figs. 7and 8.

In conformity with the specific showing of Figs. 5 and 8, the grindingelements 12, 12a are so arranged that one. holding arm 9a has at 24apivotally connected thereto a holding element 11a with two grindingelements 12a at a distance corresponding to their height, whereas theother holding arm 9 pivotally supports at 24 a holding element.-

limit switch so that the. stroke of the grinding unit in the respectiveopposite direction will be initiated.

The longitudinal axis 23 of the grinding device according to theinvention and more specifically of the guiding element 8 is slightlyinclined relative to the vertically arranged knife 3. This inclinationis such that during the upward stroke of the grinding device thegrinding elements 12, 12a move toward the knife 3. This move ment of thegrinding elements toward the knife will prevent the formation of burrnormally occurring during all grinding operations. Furthermore, thegrinding elements 12, 12a will be under uniform load so that a lineargrinding-in or grooving will be possible with the arrangement accordingto the invention. about a further improvement of the surface of thecutting edge 22.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular construction shown in the drawings butalso comprises any modification within the scope of the appended claims.

What I claim is:

1.,In combination with a cloth-cutting machine having a vertical knifewith a cutting edge: a vertically reciprocable member, holding meanssupported by said reciprocable member, grinding bodies mounted in saidholding means and angularly adjustable relative to each other so as toform different desired angles with each other, said grinding bodiesbeing composed of diamond chips bonded to each other, said holding meansbeing tiltable in a substantially horizontal plane about saidreciprocable member and being operable to press said grinding bodiesagainst the cutting edge of said knife for grinding the same, and meansfor reciprocating said reciprocable member in the longitudinal directionof said knife.

2. An arrangement according to claim 1, in which the diamond chips arebonded by ceramic binding means.

3. An arrangement according to claim 1, in which the diamond chips arebonded by vegetable binding means.

4. An arrangement according to claim 1, in which the diamond chips arebonded by mineral binding means.

5. In combination in a grinding device for grinding the cutting edge ofa vertically arranged knife of a clothcutting machine: a verticallyreciprocable member, a pair of holding arms pivotally supported by saidreciprocable member, both of said holding arms being tiltable about theaxis of said reciprocable member toward or away from each other and saidknife, a pair of holding members respectively pivotally supported at thefree ends of said arms so that each of said holding members is tiltableand adjustable about a substantially vertical axis thereby making itpossible to adjust and maintain said holding members at a differentdesired angle with regard to each other, grinding bodies mounted in saidholding members and movable by said arms into grinding engagement withopposite sides of said knife, and means for reciprocating saidreciprocable member to thereby cause said grinding bodies when inengagement with said knife to exert a grinding action thereupon.

6. In combination with a cloth-cutting machine having a verticallyextending knife with a cutting edge: a reciprocable member, holdingmeans supported by said reciprocable member, grinding bodies mounted insaid holding means and composed of diamond chips bound to each other,said holding means being operable to press said grinding bodies againstthe cutting edge of said knife This brings a 5 for grinding the same,first motor means for actuating said knife, second motor meansindependent of said first motor means for reciprocating saidreciprocable membet in the longitudinal direction of said knife, aclothpressing member adjustably mounted in said cloth-cutting machine,and contact means arranged to control the operation of said second motormeans, said contact means normally being in open position to therebyprevent oper- References Cited in the file of this patent UNITED STATESPATENTS Maimin Apr. 25, Babcock et a1. May 1, Barton July 18, LangmanMay 3, Maiman Sept. 12, Maiman Sept. 26, Root -7 June 20,

Siegel Aug. 7, Draper Mar. 4, Price Sept. 26,

